It was 20 years ago today that the world of science went crazy. Or as crazy as someone can go with a test tube in each hand. Which, as it turned out, is very crazy.

At a press conference at the University of Utah on 23 March 1989, two chemists told a stunned world that its energy worries were over. Stanley Pons and Martin Fleischmann announced that, with little more than some special water and two metal electrodes, they could harness the power of the sun in a laboratory flask. They had created a star in a jar.

The implications were extraordinary. Limitless energy. An end to the domination of the fossil-fuel industry. World peace. Cold fusion, as the effect became known, would save the day.

What Pons and Fleischmann described broke several laws of thermodynamics and all the ones about talking to the press. Stung into action, thousands of scientists tried it for themselves.

"It went nuts," says Robert Park, a physicist at the University of Maryland. "At virtually every lab in the world people were concocting ways to test it. It became a contest to prove it wrong, though they knew they would become richer and more famous if they proved it correct."

Nobody did. The laws of physics left cold fusion dead in the water. Nearly. A hardy band of believers refuses to let the dream die and, two decades on, continues to work on the phenomenon, now renamed as low-energy nuclear reactions.

"Every year there is a new great hope who we are told has the proof. Then a year later we never hear from them again," Park says. "People ask me what the legacy of cold fusion is. I prefer to ask if anything good came out of it, whether we learned anything from it. And I would say no."